In a conventional method for morphological examination of particles in urine, an examination is performed by centrifugal separation of urine particles from collected urine, and then by direct observation of the urine particles by a laboratory technician through a microscope. Such microscopic examination has such problems that (1) the result depends on the proficiency of the technician and (2) examination takes time. Accordingly, a more efficient way is demanded.
In recent years, automation of an examination of urine sediments (urine particles) has been in progress. For example, “Particle Analysis Apparatus and Particle Analysis Method (Patent documents 1 and 2)” describes a method in which a urine specimen is passed through a specially-shaped flow channel (flow cell) to pass particles in the specimen through a wide imaging region, where an enlarged image of the urine particles is taken as a static image with a flash lamp lighted.
To automatically classify a urine particle whose image is taken as a static image, the image is first divided into a region with a urine particle and a background region, and the urine particle is classified based on image feature parameters obtained for the region with the urine particle.
“Region Segmentation Method for Particle Images (Patent document 3),” for example, describes a conventional technique for dividing an image into a region with a urine particle and a background region. In this conventional technique, a method is shown in which an object region is separated from a background region based on a threshold and the magnitude of change in density value, which are obtained from a density histogram.
In addition, “Patterning Recognition Apparatus (Patent document 4)” and “Automatic Blood Cell Classification Apparatus (Patent document 5),” for example, describe conventional techniques for classifying an object based on image feature parameters. In these conventional techniques, use of a layered network as a recognition logic is described.
[Patent document 1] JP 5-296915 A
[Patent document 2] JP 63-94156 A
[Patent document 3] JP 8-145871A
[Patent document 4] JP 10-302067 A
[Patent document 5] JP 3-131756 A